Switch construction



S R DU BRIE SWITCH CONSTRUCTION Filed Sept. 30, 1944 Feb. 24, 1948.

lllll lllllllll Patented F b. 24, 1948 SWITCH CONSTRUCTION Stanley R. Du Brie, Detroit, Mich., assignor to Detroit Engineering Laboratories, Inc., Detroit, Mich., a corporation of Michigan Application September 30, 1944, SerialNo. 556,505

10 Claims. 1 This invention relates to a switch construction and more particularly to a switch.

This invention contemplates a pressure control electric switch which is of simple structure, economical to manufacture, dependable in operation and long lived.

Fig. 1 is a view of m switch showing the same partly in side elevation and partly in vertical section.

Fig. 2 is a view along the line 2--2 of Fig. 1.

Fig. 3 is a detail of the toggle arm and knif edge fulcrum bearing for the same.

Fig. 4 is a section along the line 44 of Fig. 1.

Fig. 5 is a section along the line 5--5 of Fig. 1.

Fig. 6 is a top plan view of the toggle arm assembly.

The main body I of the switch is a metal member of channel section. The pressure line or conduit 2 is connected to a source of fluid under pressure, such, for example, as the storage tank for an air compressor (not shown). Line 2 is connected by a fitting 3 to the bottom of body I by means of screws 4. The bottom of body I is provided with a circular opening 5. A flexible or rubber diaphragm 6 is mounted between fitting 3 and body I and closes opening 5. Fitting 3 is provided with a restricted or small opening 1 so that the pulsations of the fluid, either gas or liquid, in line 2 are not transmitted to diaphragm 6 but the fluid under pressure passes through opening 1 and exerts this pressure against diaphragm 6. A pressure arm 8 in the form of a metal stamping is provided at one end with two L- shaped ears 9 formed integrally therewith. Ears 9 pass through opening Ill in the bottom wall of body I to thereby hinge pressure arm 8 to body I. The other end of arm 8 is provided with an integral upturned post II to which is connected one end of tension spring I2 asat I3. The pressure arm 8 is provided witha circular indentation I4 which passes through opening 5 in body I into contact with the rubber diaphragm 6, Fig. 5. This circular indentation preferably takes the form of a fragment of a sphere. This provides an extremely cheap, simple and efficient operative connection or contact between the pressure arm and the rubber diaphragm 6 which is subjected to the changes or pressure in line 2.

Arm 8 is biased downwardly or into contact with the bottom wall of body I by pressure control spring I5 mounted upon screw I6 between nut I1 threaded on screw I6 and arm 8. By turning screw I6 in nut I1 the compression of spring I5 is varied to determine the pressure at which pressure control arm 8 will respond to open or close the switch.

. For purposes of illustration this is shown as a double pole switch. Consequently two permanent contacts I8 are shown provided with contact points I9. Contacts I8 are secured by bolts to a plate of electrically non-conducting material 20. such as a sheet of Bakelite (phenol formaldehyde condensation product) reinforced with cloth f abric. Insulating plate 20 has a snap fit in openings 2i in the side walls of body I, Fig. 4. Plate 20 also has secured thereto by bolts fulcrum bearings 22. The two line wires can be connected either to contacts III or to fulcrum bearing arms 22 by means of the usual screws 23 and 24 respectively. If the line wires are connected to contacts I8, then the motor wires, of course, will be connected to fulcrum bearings 22 and vice versa.

The pivoted contact support, in view of the fact that this is a double pole switch, comprises two contact pressure springs 25 carrying movable contacts 26 and two contact arms 21. The contact arms 21 are positioned above the contact pressure springs 25. The pressure springs and contact arms are riveted to a contact yoke 28 of insulating material such as fabric reinforced phenol formaldehyde condensation product commonly called Bakelite or Micarta.

The yoke comprises two separate sheets of insulating material one of which is positioned between arms 25 and 21 and the other of which is positioned above the same and the entire unit is secured together by rivets 30. In its mid-section the yoke has secured thereto and supports connection 3| to which one end of tension spring I2 is secured. Each of the two contact arms 25 is made from light, flat spring steel so that contact 26 makes contact lightly with contact IS. The pressure arm 2'! is made from flat, rigid steel so that as spring I2 biases the toggle arm downwardly, pressure arms 2! contact and force contacts 26 firmly into contact with fixed contacts I9. The contact toggle arms 2i are provided with knife edges 32 which pivot in the fulcrum bearings 33 of bearing arms 22. The electrical current passes through arms 25, ii. the fulcrum bearing 32, 33 and arm 22. A screw 34' is threaded through an opening in plate 20 and servesto control the differential range of the switch. The lower end of screw 34 is arranged to contact with one of the switch arms 2'! in raised position. By turning the differential screw 34 upwardly the differential range at which the switch cuts in and cuts out will be increased. By turning screw 34 downwardly this range will be decreased. The

switch can be set to cut in at twenty pounds pressure and cut out at forty pounds pressure exerted against diaphragm 6, that is, a differential of twenty pounds between cutting in and out. By means of screw 34 this differential can be varied over a wide range, for example, from ten to seventy pounds. However, the pressure at which the switch cuts out is controlled by spring l5, the compression of which is regulated by screw iBJTurning of screw 56 to increase the compression of spring l5 raises the pressure at which the switch cuts out. Turning screw IE to reduce the compression of spring I 5 reduces the pressure at which the switch cuts out.

The operation of the device is as follows: Assuming that the switch is closed with contacts 26 and I9 closed, then arms 2'! bear down on spring arms 25 to make a very firm contact. Let us assume that the switch will cut out at forty pounds fluid pressure in line 2. When the pressure in line 2 reaches forty pounds, this fluid pressure, acting through diaphragm 6 and arm 8, overcomes spring l5 and shifts the arm l3 upwardly about fulcrum 9 so that connection l3 passes above center, that is, above fulcrum 32, 33 thereby causing spring l2 to swing the toggle arm clockwise about fulcrum 32, 33 breaking contact. When contacts I9 and 26 are engaged, spring arms 25 are under tension and arms 21 hold contacts 26 firmly against contacts l9. As the toggle arm swings upwardly contacts 26 remain temporarily in contact with contacts l9 even after arms 21 start their upward movement or get under way. Asthe toggle arm gets under way it increases its speed and the tension on spring arms 25 is decreased. After the arm reaches a high speed contacts 26 pull quickly away from contacts l9 to make a very fast break. Spring 12 and the toggle arm are now in over or above center position. As the pressure in line 2 gradually falls, arm 8 pivots downwardly about pivot 9 until the assumed pressure of twenty pounds is reached whereupon connection 13 between spring l2 and post ll falls below center or fulcrum 32, 33 and the toggle switch abruptly pivots downwardly and contacts 26 and 29 are again made. Again at this time arms 21 firmly hold contacts 26 down against contacts l9 and this prevents arcing or bouncing of the contact points. Thus, in operation the toggle arm is swung to and fro about fulcrum 32, 33 with a snap action both into and out of contact.

I claim:

1. In a snap acting switch for an electric circuit, a fixed contact member, a pivoted contact member, resilient means biasing said members together to close said circuit, the pivoted contact member comprising a resilient arm adapted to contact the fixed contact member and a relatively stifi arm, a spacer between said arms, the said arms extending beyond said spacer, the said resilient arm when the contacts are closed bein flexed and under strain and the extension of said relatively stiff arm bearing against said resilient arm when the contacts are closed whereby a firm contact is maintained between the fixed and movable contacts and whereby the resilient contact arm and fixed contact member remain engaged during the initial portion of the breaking movement of said pivoted contact member and thereafter effect a fast break.

2. In a fluid pressure control switch for an election in direct contact with said diaphragm and controlled by the dilation and contraction of said diaphragm, a. fixed contact memberI a pivoted contact member arranged to pivot to one side of center to close said contacts and to the other side of center to open said contacts, resilient means for biasing said pivoted contact member over center toward closed or open position, and means connecting said pivoted control member to said pivoted contact member whereby changes in the fluid pressure exerted on the diaphragm causes said contact member to pivot over center to open or close said contacts.

3. In a fluid pressure control switch for an electric circuit, a frame member having an opening therein, a flexible diaphragm closing said opening and adapted to be influenced by fluid under pressure, a control-arm pivoted to said frame and having an integral stamped indentation adapted to contact with said diaphragm through said opening in the frame, a fixed contact member and a pivoted contact member arranged to swing to one side of center to close said contacts and to the other side of center to'open the same, resilient means for biasing said pivoted contact member over center to closed position, and an operative connection between said control arm and the pivoted contact whereby pivoting of the control arm by a change in fluid pressure against said flexible diaphragm causes said spring to bias the pivoted contact member to the other side of center. i

4. In a snap acting switch for an electric circuit, a fixed contact member, a pivoted contact member, resilient means biasing said members together to close said circuit, the pivoted contact member comprising a resilient and a relatively stiff arm, the resilient arm being positioned between the stiff arm and the fixed contact member, a pivot for said pivoted contact member at the end of said arms remote from the fixed contact member, the said relatively stifi and resilient arms being spaced from each other when the switch is in open position and the end of the relatively stifi arm adjacent the contact end of the resilient arm bearing against and holding the resilient arm into firm contact with the fixed contact member when the switchis closed, the said resilient armbeing flexed as the switch closes whereby as the switch opens the resilient contact arm remains in contact with the fixed contact member during the initial portion of the opening movement and then effects a fast break.

5. In a snap acting switch for an electric circuit, a support member, a fixed contact arm supported by said support member, a fulcrum arm also supported by said support member and spaced from said fixed contact arm, a pivoted contact member pivoted at one end on the fulcrum arm, the said pivoted contact member comprising a resilient metal strip and a relatively stiff metal strip positioned between the relatively stiff metal strip and the fixed contact arm, a spacer between said arms and extending throughout a. portion of the length of said arms whereby in open position the extended portions of said relatively stifi and resilient arms are in spaced relation, resilient means for biasing said pivoted contact arm into closed position whereby during the final closing movement of the pivoted contact member the resilient contact arm contacts the fixed contact member and flexes about said spacer and the relative stifi arm bears against the end of the resilient arm and holds the same into firm contact with the fixed contact member whereby ontrol member to said pivoted contact member whereby the contact members are opened and closed with a snap action by changes in the fluid pressure exerted on the diaphragm.

'7. In a fluid pressure control switch for an electric circuit, a frame having an opening therein, a flexible diaphragm closing said opening and adapted to be influenced by fluid under pressure, a control member having an integral indented portion contacting said diaphragm through said opening and controlled by the dilation and contraction of said diaphragm, and contact mechanism actuated by said control member as the diaphragm dilates and contracts, said frame member having a pair oi'hlnge openings and said control member having a pair of integral cars which engage the frame in said hinge opening to form a hin e for said control member.

8. In a snap acting switch for an electric circuit, a support member of insulating material, a flxed contact arm supported by said support memher. a fulcrum arm also supported by said support member and spaced from said flxcd contact arm, a pivoted contact member pivoted at one end on the fulcrum arm and adapted to contact the flxed contact arm to close the circuit. said flxed contact serving as a stop for said pivoted contact member, and connections on the fixed contact arm and on the fulcrum arm for electrically conducting lines whereby when the switch is closed the current flows in circuit through the flxed contact arm, the pivoted contact member and the fulcrum arm.

9. In a fluid pressure control switch for an electric circuit. a flexible diaphragm adapted to be influenced by fluid under pressure, a pivoted control member having an integral portion in direct contact with said diaphragm and controlled by the dilation and contraction of said diaphragm, a

fixed contact member, a pivoted contact member arranged to pivot to one side of center to close said contacts and to the other side 01' center to open said contacts, resilient means for biasing said pivoted contact member over center toward closed or open position, a connection between said resilient means and said pivoted contact member, an anchor for connecting said resilient means to said pivoted. control member, said anchor being moved to one side or the other of center by said pivoted control member as the diaphragm responds to changes in fluid pressure whereby said resilient means pivots said contact member over center with a snap action into or out of engagement with said fixed contact member.

10. In a fluid pressure control switch for an electric circuit, a flexible diaphragm adapted to be influenced by fluid under pressure, a pivoted control member having an integral portion in direct contact with said diaphragm and controlled by the dilation and contraction of said diaphragm, a fixed contact member, a pivoted contact member arranged to pivot to one side of center to close said contacts and to the other side of center to open said contacts, a tension spring for biasing said pivoted contact member over center toward closed or open p sition, a connection between one end of said spring and said pivoted contact member, an anchor for connecting the other end of said spring to said pivoted control member, said anchor being moved to one side or the other of cehter by said pivoted control member as the diaphragm responds to changes in fluid pressure whereby said tension spring pivots said contact member over center with a snap action into or out of engagement with said flxed contact member.

STANLEY R. DU BRIE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 706,260 Schureman Aug. 5, 1902 1,903,924 Irwin Apr. 18, 1933 1,985,337 Bondurant Dec. 25, 1934 2,281,544 Beeman et al. May 5, 1942 2,302,923 Zimarik Nov. 24, 1942 

